A galoof is generally used as an adjective, to describe one who is abnormally large and clumsy.
It of course comes from the word Goof except some complete idiot mispelled it for some reason or another.
That young lad over there is such a galoof, oh look he just hit his head on a ceiling fan.
Stands for Non-Educated Delinquent. The stereotype is someone who wears white tracksuits, burbery cap, has a bottle of Buckfast (cheap alcohol) in his/her hand. Generally applied to the violent NED stereotype.